The efficacy, safety and tolerability of sildenafil in the treatment of men with erectile dysfunction have been demonstrated in numerous studies of 1 year duration or less. Viagra Cost For example, 1,358 men with erectile dysfunction completed 1 of 4 double-blind trials and continued open-label sildenafil treatment in extension studies for a total treatment duration of approximately 1 year. In the current study, 979 of these men subsequently received up to 4 more years of open-label, flexible-dose Cost of Sildenafil citrate (25, 50, and 100 mg).